N11型EM直流毫微电压计是对极低功率直流电位测量多年研究的结果。取自于多种EM毫微电压计的经验最终促成了N11的设计。
须采取特别的措施，确保输入级对测量的主体造成的干扰最小。根据设计，N11是在极低功率的敏感电路中运行。无需过多照看，在输入阻抗提升至1000MΩ时，有可能化解1×10-4瓦特的层次。如果N11与数字电压计共同使用，就可展示1×10-4伏特比特，并且保持闪烁程度最小。此外，根据设计，这一工具还拥有很高的线性。
N11型EM直流毫微电压计能在遵循电源“约翰逊”噪声特性的情况下，在10Ω到100000Ω的范围内，且在范围宽广的电阻条件下对电源进行衡量，这是其诸多重要特点之一。这意味着N11，在室温条件下，可以被有效的用来测量氮温度中的电源，即使在氮3温度情况下开展某些测量。（参见电源电阻噪声电压图）。
该仪器卓越的稳定性使其成为长期偏移测量的理想工具，它还能被连接至记录器上，也可长期无人值守。
操作人员可以借助6位低通滤波器对响应时间实施控制，并降低受到测量的电路噪声。
具备11个点位的多功能开关，具备刻度补偿电压控制功能，拥有正负1毫伏的回退能力。可将其用于衡量相对较大信号中的较小变化，在任何范围内对输入等级的补偿将得到刻度电位计的补偿，补偿率大约为0.01%。
纯铜输入终端确保可以对输入放大器保持很高的热稳定性，同时能够较为便利的连接至该仪器上。
在仪器尾部由两个输出，一个是直接的输出，另一个是隔离的输出。虽然隔离器同时也具备良好的线性，但是当需要较高的线性时，将使用直接输出，N11内装有可置换电池，因此可对其进行彻底隔离。对这一仪器进行工程调教，使其保持较高的标准，并与终端护罩上的插头融为一体。
The EM DC Nanovoltmeter model N11 is the result of years of development in the measurement of very low level DC potential. All the experience gained from the EM range of Nanovoltmeters has gone into the design of the N11.
Special care has been taken to ensure that the input stage causes the least possible disturbance to the subject being measured, and the N11 is designed to operate in sensitive circuits at very low levels. With a little care, it is possible to resolve levels of 100 picovolts, with an input impedance which increases to over 1000 Mohm with time. If the N11 is used in conjunction with a digital voltmeter, 100 picovolt bits may be displayed with a minimum of flicker. The instrument is also designed to have a high degree of linearity.
One of the very important features of the N11 is its ability to measure sources with a wide range of impedance, by following the source 'Johnson' noise characteristic closely from 10 ohms to over 100K ohms. This means that the N11, while remaining at room temperature, may be used efficiently to measure a source at helium temperature, and even at helium 3 temperature for some measurements. (See the graph of noise voltage against source resistance).
The excellent stability of this instrument makes it ideal for long term drift measurements, and it may be connected to a recorder and left unattended for long periods.
The six position low pass filter gives the operator control over the response time and reduction of noise from the circuit being measured.
A calibrated offset voltage control is provided, with an eleven position multiplier switch, giving a maximum back-off capability of plus and minus one millivolt. This can be used to measure small changes in comparatively large signals. the level of input which can be offset on any range will be limited only by the resolution of the calibrated potentiometer, i.e. about 0.01%.
The pure copper input terminals ensure that the very high thermal stability of the input amplifier is maintained, and also that connection to the instrument may be made easily.
There are two outputs at the rear of the instrument, one direct and the other isolated. When a high linearity is required, the direct output should be used, if possible, although the isolator also has a good linearity.
The N11 is battery operated from internal chargeable batteries and so has the advantage of complete isolation. This instrument is engineered to a very high standard and comes complete with a plug on terminal shield.
N11直流毫微电压计说明
范围
输入范围的1： 12倍， ± 10nV fsd---- ± 3mV fsd。
输入范围的2： 12倍， ± 10mV fsd---- ± 1KV fsd。
Range
Input 1. 12 ranges. +/- 10nV fsd to +/- 3mV fsd
Input 2. 12 ranges. +/- 10mV fsd to +/- 1KV fsd
精确度
直接输出： ± 0.2%
隔离输出： ± 0.5%
仪器： ± 1.5%
Accuracy
Direct Output. +/- 0.2%
Isolated Output. +/- 0.5%
Meter. +/- 1.5%
线性
直接输出优于100ppm
Linearity
Direct output better than 100 ppm
零度偏移
优于每摄氏度500pV.
Zero Drift
Better than 500pV per degree C.
噪声
同等噪声阻抗大约为10Ω。噪声电压取决于滤波器设置，即：滤波时间为10秒常数，在输入短路的情况下，创造的噪声Vp-p大约为250×10-6V。
Noise
Equivalent noise resistance approximately 10 ohms. Noise voltage depends on filter setting, e.g. filter time constant 10 seconds gives peak to peak noise voltage of approximately 250 picovolts with the input short circuited.
电源电阻
电源电阻低于10Ω，仪器噪声稳定的降低至0Ω。随着电源电阻从10Ω上升至数百Ω，仪器细微的提升了电源噪声。在高于100kΩ的情况下，仪器噪声以电源电阻提升10进制的20dB。N11运行的范围上限高达1MΩ。
Source Resistance
With a source resistance of less than 10 ohms, the instrument noise is substantially constant down to zero ohms. With source resistance from 10 ohms to a few hundred K ohms, the instrument adds insignificantly to the source noise. Above 100K ohms the instrument noise increases at about 20dB per decade of source resistance. The N11 will operate with sources up to about 1 M ohm.
解析度
极大滤子情况下，1×10-4V。
Resolution
100 picovolts with maximum filter.
输入阻抗
输入1：高于30MΩ，阶跃输入后3秒，随着时间推移上升至1GΩ。
输入2:10 MΩ
Input Impedance
Input 1. Greater than 30 M ohm, 3 seconds after a step input, increasing with time to over 1 G ohm.
Input 2. 10 M ohm
补偿电流
可在前端面板上调整至0。温度系数优于1pA/℃。
Offset Current
Adjustable to zero at the front panel. Temperature coefficient better than 1pA per degree C.
响应时间常数
取决于滤波器的设置和范围。最低250毫秒，最大40秒。
Response Time Constant
Depends on setting of filter and range. Minimum. 250 milliseconds. Maximum. 40 seconds.
滤波器
位于前端面板的开关控制的低通量滤波器上的6个点位。
Filter
Six position low pass filter operated by a switch on the front panel.
补偿
10刻度电位计，刻度范围为0-1000，带有11个电开关，最大补偿为正负100nV, 1uV, 10uV, 100uV, 1mV以及1个0位。解析度：优于0.01%。精确度：优于0.5%。
Offset
10 turn potentiometer calibrated 0-1000 with eleven position switch giving maximum offsets of plus and minus 100nV, 1uV, 10uV, 100uV, 1mV and a '0' position. Resolution. Better than 0.01%. Accuracy. Better than 0.5%.
串联方式抑制
在50Hz时大于80dB。
Series Mode Rejection
Greater than 80dB at 50Hz.
输出
直接和隔离的输出为满刻度偏移设定了±1V的范围。放大器增益等同于设定的伏特范围。
Outputs
Direct and isolated outputs give plus and minus 1V for full scale deflection. Amplifier gain equals the reciprocal of the range setting in volts.
隔离
机箱输入或输出。大于100GΩ。
Isolation
Input to case or output. Greater than 100G ohm.
连接器
输入1：EM低热电势终端。在“输入2”和“机箱”中，借助4毫米的插座旋紧终端。输出：尾部的4毫米插座。配备一个插在终端上的插座。
Connectors
Input 1. EM low thermal emf terminals. Screw terminals with 4mm sockets for 'Input 2' and 'Case'. Outputs. 4mm sockets at rear. Plug on terminal cover provided.
仪表
105毫米镜面表盘，刻度为10-0-10以及3-0-3。
Meter
105mm mirror scale calibrated 10-0-10, and 3-0-3.
电源
内部可置换电池，满充电情况下可以运行50小时。主干线充电器在16小时内为电池充满电，并在仪器关闭时或20小时后使用。电源要求为240V或者110V，50Hz或60Hz。可从外部、低噪音和电源中对电池进行充电。最低电压：20V。电池容量：1.2AH。外部充电器必须为交流电源。
Power Supply
Internal chargeable batteries, giving more than 50 hours operation from a full charge. Mains powered charger fully charges the batteries in 16 hours with the instrument switched off or 20 hours when in use. Power required 240V or 110V. 50Hz or 60Hz. 5VA. There is an alternative input to charge the batteries from an external, low noise, current source. Minimum voltage. 20V. Battery capacity. 1.2AH. NB. External charger must be a current source.
规格
深度： 314毫米 (12.4英寸)
深度： 322毫米(12.7英寸)
高度： 179毫米 (7英寸) 包括折叠脚。
Dimensions
Width. 314mm (12.4")
Depth. 322mm (12.7")
Height. 179mm (7") Including folded feet.
重量
12千克 (26.5磅)
Weight
12Kg (26.5lbs) |